AOC vs ADT: Two Names for the Same Reagent

Buy oligo-tagged antibodies for more than one application and you hit a naming problem. A spatial biology paper calls the reagent an antibody-oligonucleotide conjugate, or AOC. A CITE-seq protocol calls the same kind of molecule an antibody-derived tag, or ADT. Suppliers split the same way, with some listing AOCs, some listing ADTs, and a few using both, even though they all mean the same reagent.

This article sets out what the two terms mean, why each field picked its own name, and which one to use when you are reading papers or searching for reagents.

The Same Molecule in Both Fields

At the bench, an AOC and an ADT are the same thing: an antibody covalently linked to a short DNA oligo that works as a barcode, a capture sequence, or a docking site. Which name you use depends on your field. Conjugation chemists and reagent suppliers call it an AOC, while single-cell immunologists running CITE-seq call it an ADT, and both are standard usage where they come from.

Where the Two Names Came From

The two words started on different parts of the experiment, which is the easiest way to keep them straight.

AOC began as a chemistry term for the reagent, an antibody joined to an oligo by a defined conjugation. It says nothing about what the oligo does next, which is why it carries over to applications that have nothing to do with sequencing, from proximity ligation assays to DNA-PAINT imaging.

ADT began with the readout. In CITE-seq the oligo on each antibody is a barcode that gets sequenced, and the counts you analyze per cell are the antibody-derived tags. But the name did not stay on the data. Single-cell groups spend their time counting and normalizing ADTs, so they call the reagent an ADT as well. In that field the one word covers both the antibody you add to the cells and the numbers you get back, and AOC rarely comes up.

So a supplier sells you an AOC, you run it in CITE-seq, and to that field both the reagent and the counts are ADTs. It is the same molecule, named differently depending on who is describing it.

AOC: Chemistry, Proximity Assays, and Spatial

AOC is the standard term in bioconjugation and reagent manufacturing. Chemistry reviews use antibody-oligonucleotide conjugate for the whole class, across detection, imaging and therapeutics, and often introduce it alongside the antibody-drug conjugate (ADC).

In detection and imaging it is the usual name for proximity assays such as PLA and PEA, for immuno-PCR, and for DNA-PAINT. Custom-conjugation suppliers, the closest match to what AbOliGo does, brand the reagent as an antibody-oligo conjugate and list CITE-seq, cell barcoding, multiplexing and proximity ligation together under it. In the spatial and multiplexed-imaging literature, AOC is used throughout and ADT almost never appears.

If the context is the chemistry of the reagent, or any application outside single-cell sequencing, AOC is the right word. That is why most of the AbOliGo knowledge hub, written from a conjugation and applications angle, uses AOC.

ADT: CITE-seq and Single-Cell Tools

In single-cell work the naming changes. ADT is the standard here, and it goes deeper than everyday usage: the term is written into the analysis software. The groups that developed CITE-seq defined the readout as antibody-derived tags, and the term is now part of the tools everyone uses.

In Seurat, the main single-cell analysis package, protein data lives in an assay named ADT. Normalization methods are named after it: the dsb method calls itself ADT normalization, and ADTnorm exists specifically to normalize ADT counts across datasets.

For a reagent buyer this matters in practice. In CITE-seq papers and analysis tutorials, AOC barely appears, even though the reagents are chemically antibody-oligonucleotide conjugates. Talk only about AOCs to a single-cell audience and you read as an outsider. That is why AbOliGo pages aimed at that audience, such as the custom CITE-seq and feature barcoding service and the guide to optimizing single-cell staining, use ADT alongside AOC.

Related Terms to Know

A few related terms sit around AOC and ADT. Knowing them helps when you read papers or search for reagents.

HTO (hashtag oligonucleotide) is the single-cell counterpart to ADT for a different job. An ADT measures a surface protein. An HTO labels a whole sample so pooled samples can be separated again after sequencing, which is cell hashing. Seurat stores hashing data in its own assay, named HTO. If you are multiplexing samples rather than measuring protein, HTO is the term to search.

DNA-barcoded antibody and feature barcode antibody are descriptive phrases that turn up alongside ADT in single-cell content, the second tied to 10x feature barcoding. Oligo-conjugated antibody is a neutral description both fields understand.

Watch the ADT Acronym

One reason to write out antibody-derived tag rather than lean on the acronym is that ADT means several other things outside biology. In medicine it usually means androgen deprivation therapy, a common prostate-cancer treatment. In software it can mean abstract data type or Android Development Tools, and ADT Inc. is a security company. The general disambiguation page for ADT does not even list an antibody meaning.

When reading papers this rarely causes trouble, because context makes it clear. It matters when you search. A plain search for ADT returns oncology and software results first. Add context, such as CITE-seq ADT, ADT antibody, or antibody-derived tag, and you get to the reagents. The same point applies to anyone writing content in this area.

Which Term to Use

Match the term to the field.

Working in conjugation chemistry, proximity assays, spatial biology or imaging, use AOC or the full antibody-oligonucleotide conjugate. Working in CITE-seq, cell hashing or feature barcoding, use ADT, and use HTO when you mean hashing. Writing for a mixed audience, define both the first time: a custom ADT is the antibody-oligonucleotide conjugate used as the protein readout in CITE-seq.

For AbOliGo the reagent is the same either way. Whether you need AOCs for a proximity ligation assay, ADTs for a CITE-seq panel, or conjugates for spatial and imaging work, it is one custom conjugation service making the molecule your workflow needs. For more on how these reagents are used across fields, see the overview of scientific techniques using antibody-oligonucleotide conjugates.

References

• CITE-Seq overview (Stoeckius et al., original method; ADT terminology).
• Satija Lab. Seurat Hashing Vignette (ADT and HTO assays in the analysis tools).
• dsb: an end-to-end CITE-seq ADT normalization workflow. CRAN.
• ADTnorm: normalization of antibody-derived tag abundance across CITE-seq datasets. Nature Communications. 2025.
• Antibody-Oligonucleotide Conjugates as a Novel Class of Reagents. Bioconjugate Chemistry review (AOC terminology).
• ADT disambiguation (acronym overlap).